The following includes information that may be useful in understanding the present invention(s). It is not an admission that any of the information provided herein is prior art, or material, to the presently described or claimed inventions, or that any publication or document that is specifically or implicitly referenced is prior art.
1. Field of the Invention
The present invention relates generally to the field of truss lifting devices and more specifically relates to a cam hook truss lift system for lifting and positioning building trusses into position.
2. Description of the Related A
When constructing a building with a pitched roof design it is typically necessary to use trusses. Trusses are generally composed of triangles because of the structural stability of that shape and design; thus providing a pitch to shed precipitation. A triangle is the simplest geometric figure that will not change shape when the lengths of the sides are fixed. A series of triangles are assembled together forming a desired length for the roof of the building under construction. Trusses are normally pre-assembled to the specified length and delivered to the construction site and must be put in place by on-site workers.
Typically a roofing crew waits in position for the trusses to be lifted up to them so they can place them and attached them according to specifications. However, trusses are typically long and cumbersome to handle making it difficult and dangerous to hoist the truss to the workers on the roof level and then put them in place. Many times workers need to climb ladders or scaffolding in a coordinated fashion while carrying the truss to reach the roof level resulting in potential injuries to the workers and possible damage to the truss if it is dropped. Several workers are often required to work together to hoist the trusses to the roof level. Sometimes it is necessary to pull workers from other disciplines working on the building, such as electricians and plumbers, in order to have enough manpower to lift the trusses to the required height. When this happens, the work that is abandoned to help with the trusses may fall behind schedule resulting in other problems with completing the overall project. It is desirable to have a safe and convenience means by which trusses can be lifted and placed during construction.
Various attempts have been made to solve the above-mentioned problems such as those found in U.S. Pat. No. 4,240,658 to Britson; U.S. Pat. No. 5,178,427 to Jorritsma; U.S. Pat. No. 3,165,344 to Holder; U.S. Pat. No. 4,475,758 to Paulsson; U.S. Pat. No. 2,133,557 to McNeillie et al; and RE28709 to Crook. This prior art is representative of devices to lift trusses. None of the above inventions and patents, taken either singly or in combination, is seen to describe the invention as claimed.
Ideally, a cam hook truss lift system should provide a quick and an easy-to-use device to lift and place building trusses, and yet, would operate reliably and be manufactured at a modest expense. Thus, a need exists for a reliable cam hook truss lift system to avoid the above-mentioned problems.